Given the fervor over vegetarianism, you’d think it’s something new. It’s not. It’s a tenant of Hinduism and Buddhism, and past advocates of a plant-based diet range from Pythagoras to Tolstoy to Hitler. Reasons to become a vegetarian include health and ethics, and proponents tell us that it needn’t be an all or nothing proposition. If you aspire to be one—or to feed one—here are some permutations.

Vegetarian: Abstains from animal flesh.

Ovolactarian, ovo-lacto-vegetarian: Eats eggs and dairy, but no meat. Simplest way to assure adequate protein without meat.

Lactarian, lacto-vegetarian: Dairy, yes. Eggs, no.

Ovo-vegetarian: Eggs, yes. Dairy, no.

Pescetarian: Land animals are off the menu, but fish is fine.

Vegan: Abstains from all animal products, including eggs and dairy, as well as less obvious offenders like honey and gelatin. Serious vegans don’t wear wool, silk or leather and check toothpaste labels to avoid calcium derived from animal bones.

Semitarian: A flexitarian with rules, generally a schedule for when meat can be eaten. Cookbook author and food writer Mark Bittman, for example, is a “vegan until dinner,” when all bets are off.

Raw foodist: In the belief that cooking kills nutrients, avoids foods heated above 115F. May or may not be vegetarian; some raw foodies frequent sushi bars. Usually passionate about juicing and sprouting, raw foodists “bake” through dehydration. Reported benefits include weight loss and heightened energy.